Revolutionary Discovery Extends Lifespan of Lithium-Ion Batteries!

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A team of researchers led by Professor Jihyun Hong from the Department of Battery Engineering at the Graduate Institute of Ferrous & Eco Materials Technology at POSTECH, in collaboration with Dr. Gukhyun Lim, has devised an innovative approach to enhance the longevity of lithium-rich layered oxide (LLO) materials, which serve as next-gen cathodes for lithium-ion batteries (LIBs). This advancement, which considerably prolongs battery life, was documented in the prestigious energy journal Energy & Environmental Science.

Lithium-ion batteries are crucial in fields like electric vehicles and energy storage systems (ESS). The lithium-rich layered oxide (LLO) material provides up to 20% greater energy density compared to traditional nickel-based cathodes by decreasing the nickel and cobalt amounts while increasing the lithium and manganese proportions. As a cost-effective and sustainable option, LLO has attracted considerable interest. Nevertheless, issues like capacity loss and voltage drop during charge-discharge cycles have obstructed its commercial success.

While earlier studies have pinpointed structural transformations in the cathode during cycling as the source of these problems, the specific causes of the instability have remained mostly unclear. Moreover, current methods to bolster the structural stability of LLO have been insufficient in addressing the underlying issue, impeding commercialization.

The POSTECH team concentrated on the essential role of oxygen release in compromising the stability of the LLO structure throughout the charge-discharge cycle. They theorized that enhancing the chemical stability of the interface between the cathode and the electrolyte could avert oxygen release. Building upon this premise, they strengthened the cathode-electrolyte interface by refining the electrolyte composition, leading to a significant decrease in oxygen emissions.

The improved electrolyte developed by the research team maintained an impressive energy retention rate of 84.3% even after 700 charge-discharge cycles, a remarkable advancement compared to traditional electrolytes, which typically achieved just 37.1% energy retention after 300 cycles.

The investigation also indicated that structural modifications on the surface of the LLO material crucially influenced the overall stability of the material. By tackling these changes, the team was able to notably enhance the lifespan and efficiency of the cathode while also reducing detrimental reactions such as electrolyte decomposition within the battery.

Professor Jihyun Hong remarked, “Utilizing synchrotron radiation, we could investigate the chemical and structural distinctions between the surface and the core of the cathode particles. This uncovered that the stability of the cathode surface is vital for the overall structural integrity of the material and its performance. We are optimistic that this research will offer new pathways for the advancement of next-generation cathode materials.”

Reference: Lim G, Cho MK, Choi J, et al. Decoupling capacity fade and voltage decay of Li-rich Mn-rich cathodes by tailoring surface reconstruction pathways. Energy Environ Sci. 2024;17(24):9623-9634. doi: 10.1039/D4EE02329C

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